Arctic Tundra Vegetation Dynamics under Changing Environmental Conditions

Yu, Qin, Department of Environmental Sciences, University of Virginia
Epstein, Howard, Department of Environmental Sciences, University of Virginia
Shugart, Herman, Department of Environmental Sciences, University of Virginia
D’odorico, Paolo, Department of Environmental Sciences, University of Virginia
Ford, Roseanne, Department of Chemical Engineering, University of Virginia

The Arctic is a system with strong interconnectedness among components and now is experiencing dramatic alterations due to climate change. With amplified climate warming and greater accessibility to the Arctic, anthropogenic factors such as industrial development, climate change, and animal husbandry have become increasingly important to arctic ecosystems. The objective of this dissertation is to use a vegetation model and remote sensing to better understand the dynamics of the arctic tundra biome in a chaning environment with emphasis on the effects of climate, soils, grazing and land use. I examined the individual and interaction effects of climate change and reindeer grazing, across a variety of climate zones and soil texture types, on tundra vegetation community dynamics using an arctic vegetation dynamics model at regional and circumpolar scales. At the regional scale (on the Yamal Pensinula of northwestern Siberia), I found that grazing and warming affect tundra plant communities in opposite directions with significant interaction effects. The grazing impact can be the most important factor controlling tundra plant community composition and structure, aside from the latitudinal climate gradient. Grazing and warming can initiate shifts in tundra plant communities due to differential responses of different plant functional types. Initial vegetation responses to climate change during transient warming are different from the long term equilibrium responses due to shifts in the controlling mechanisms (nutrient limitation vs. competition) on tundra plant communities.I also examined effects of climate change and grazing across the pan-Arctic and found that grazing can abate the tundra plant response to climate change and complicate our interpretation of the "greening" trend in the arctic tundra. II As land use has become a conspicuous factor that affects tundra plant communities, the magnitude of land cover and land use changes and the persistence of their effects remain unknown. I examined land use change effects on an oil/gas facility area at Nadym, Russia with multi-sensor and multi-temporal remotely sensed imagery. Exploration of oil/gas and associated development denuded surface vegetation and impacts of this development can last for several decades, although some recovery of vegetation was also found after extensive land use changes. Changing climate interactions with grazing yielded complex responses in tundra vegetation. Additionally, land use as a controlling factor on tundra vegetation dynamics cannot be ignored in the Arctic, as vegetation recovers slower than in other parts of the world.

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PHD (Doctor of Philosophy)
climate change, arctic, ecosystem, animal husbandry, tundra plant
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